exclude device from bus probe?

[Göran Löwkrantz]

We have a system based on Supermicro X7SPA-HF with IPMI connected via a 
shared 82574L NIC. We are not using this NIC for anything from the OS but 
the probing and device attach breaks the IPMI connection so bad FBSD don't 
see any screen during boot. There is no BIOS flag that disables the NIC 
from the OS, only a HW strap but that dsables the IPMI also.

Is it possible to disable the probe of the NIC using hists to the PCI bus 
driver? I have addded hint.em.0.disable=1 but it does not help.

em0 at pci0:2:0:0:	class=0x020000 card=0x10d315d9 chip=0x10d38086 rev=0x00 
hdr=0x00
    vendor     = 'Intel Corporation'
    device     = '82574L Gigabit Network Connection'
    class      = network
    subclass   = ethernet

Any other suggestions appreciated.

/glz